Decommissioning Insight 2016

8. Appendices

Work Breakdown Structure and Survey Methodology

Operators were asked to provide expenditure forecasts for the 20 different components of the Work Breakdown

Structure outlined in Oil & Gas UK’s

Decommissioning Cost Estimation Guidelines

. They were also asked to

quantify physical decommissioning activity by components, such as the tonnes of topsides to be removed or the

length of pipeline to be 'made safe'.

The

Decommissioning Insight

report has been produced annually since 2011. Although it is possible to compare

data across the reports, it is important to note that since 2013 surveys have been modelled on a new Work

Breakdown Structure. Historical analysis has therefore only been carried out on comparable categories.

Figure 46: Work Breakdown Structure Categories

Stages - Level 1

Operator project

management

Activities include project management core team, stakeholder engagement, studies

to support the decommissioning programme and scope definition/method

development, decommissioning programme preparation and decommissioning

programme reporting/close-out (admiralty charts, fish safe etc).

Facility running/

owners' costs

Activities include logistics (aviation and marine), operations team, deck crew,

power generation, platform services, integrity management (inspection and

maintenance) and operations specialist services e.g. waste management.

Well plugging and

abandonment

Activities include rig upgrades, studies to support well programmes, well

suspension (spread rate/duration), wells project management, operations support,

specialist services e.g. wireline, conductor recovery, cleaning and recycling, vessels.

Facilities/pipelines

'making safe'

Activities include operations (drain, flush, purge and vent), physical isolation

(de-energise, vent and drain), cleaning, pipeline pigging and waste management.

Topsides preparation

Activities include engineering-up of temporary utilities (power, air and water),

module process/utilities separation, dropped object surveys and subsequent

remedial actions.

Topsides removal

Activities include removal preparation (reinforcements and structural separation

for removal), vessel operations, sea-fastening, transportation and load-in.

Substructure removal

Activities include removal preparation, removal, vessel, sea-fastening,

transportation and load-in.

Topsides and

substructure onshore

recycling

Activities include cleaning and handling hazardous waste, deconstruction,

re-use, recycling, disposal and waste management accounting

(traceability of all streams).

Subsea infrastructure

(pipelines, umbilicals)

Activities include vessel preparation for subsea end-state (remove, trench,

rock-dump), sea-fastening and transportation, load-in, subsea project management

and waste management accounting (traceability of all streams).

Site remediation Activities include cuttings pile management, oil field debris clearance

(500-metre zone and 200-metre pipeline corridor) and over-trawl surveys.

Monitoring

Activities include navigation aids maintenance and monitoring programme

for any facilities that remain.

The

Guideline on Decommissioning Cost Estimation

is available to download at